Gate using variable cathode follower impedance for shorting or passing cathode-fed impulses



p 1958 R. M. STRASSNER ET AL GATE. USING VARIABLE CATHODE F OLLOWERIMPEDANCE FOR SHORTING OR PASSING CATHODE-FED IMPULSES Filed May 12,1954 IOK IOK BIA SING MEANS NEGATIVE PULSE SOURCE fIQ FIG. 2. (b)

INVENTORS. ROBERT M. STRASSNER EVERETT 6. SHOVER KBW A T TORNE V UnitedStates Patent F GATE USING VARIABLE (IATHODE FOLLOWER IMPEDANCE FORSHORTING R PASING CATHODE ED IMPUIQES Robert M. Strassner, (Zhicago,111., and Everett G. Shover, Arcadia, Qalif, assignors, by mesneassignments, to Consolidated Electrodynamics Corporation, Pasadena,Calif., a corporation of California Application May 12, 1954, Serial No.429,353

4 Claims. (Cl. 250-27) The present invention relates to signal transfercircuits and more particularly to circuits for selectively passingelectrical impulses to an output circuit.

In electrical systems such as digital computing apparatus, a binarycounter for counting a selected number of electrical pulses isfrequently employed. Where four bistable circuits are employed as abinary counter the total number of permutations in the conditions ofconduction of the bi-stable circuits equals 16. For some applications,however, it is desirable to limit the maximum count to a lesser number,say 10 counts. This may be accomplished by inhibiting the passage ofcounting impulses to selected ones of the bi-stable circuits so that oneor more of the possible permutations is omitted.

In accordance with our invention we have provided an improved andsimplified circuit for controlling the passage of electrical impulses toan output circuit, which may comprise a selected one of the bi-stablecircuits in a binary counter.

In one embodiment, our invention includes an electron tube having acathode, a primary anode, a control electrode, and two auxiliaryelectrodes adjacent to the cathode. By connecting a cathode resistorbetween the cathode and a reference potential, a back voltage isprovided at the cathode by the passage of current between the cathodeand the primary anode which tends to diminish current flow between thecathode and the auxiliary anodes. A source of negative pulses is coupledacross the cathode resistor, an output circuit is connected to theauxiliary anodes, and a biasing means is coupled to the controlelectrode.

A better understanding of the operation and advantages of our inventionmay be had upon a reading of the following detailed description whentaken in connection with the drawings, in which:

Fig. 1 is a combination block and schematic diagram of one embodiment ofour invention; and

Fig. 2 is a graphical representation of certain of the electricalsignals appearing in the embodiment of Fig. 1.

Referring in detail to Fig. 1, a signal transfer circuit is shown whichincludes an electron tube 3 having a primary anode, a control electrode,a cathode, and two auxiliary anodes 5 and 7. Several commercial electrontubes, which are readily available, include all of these electrodes.Ordinarily the auxiliary anodes are employed as second detectors andautomatic volume control indicators in superheterodyne radios. Theauxiliary anodes 5 and 7 share the cathode of the electron tube 3 withthe primary anode.

A cathode impedance, such as a resistor 9, is connected between thecathode and a reference potential. The anode of the electron tube 3 maybe energized by means of a terminal 11 which is adapted to be connectedto a suitable source of positive potential (not shown). Biasing means13, which is connected to the control electrode of the electron tube 3,provides a control potential for varying the flow of current between thecathode and the anode, and hence the voltage appearing across thecathode re- 2,854,572 Patented Sept. 30,1958

current flow between the cathode and the auxiliary anodes 5 and 7. Onthe other hand, if the voltage across the cathode resistor 9 isrelatively small, the negative pulses from the negative pulse source 15drive'the cathode negative with respect to the auxiliary anodes 5 and 7,thereby causing conduction and a negative pulse to pass to the outputcircuitry connected to the auxiliary anodes.

The relationship of the electrical signals involved is shown in Fig. 2wherein Fig. 2(a) illustrates the signal provided by the inhibitingmeans 13in two conditions of operation. When the signal from the biasingmeans 13 is low, as indicated at 17, the negative pulses from thenegative pulse source 15, as illustrated in Fig. 2(b), are passed to theoutput circuitry associated with the auxiliary anodes 5 and 7 as shownin Fig. 2(a).

On the other hand, when the signal provided by the biasing means 13 ishigh, as illustrated in Fig. 2(a) at 19,

the negative pulses provided by the negative pulse source 15, asillustrated in Fig. 2(b), do not appear at the auxiliary anodes 5 and 7as illustrated in Fig. 2(c).

The particular output circuitry associated with the auxiliary anodes 5and 7 of the illustrative embodiment of Fig. l is a conventionalbi-stable circuit including two cross-coupled electron tubes 21 and 23.The circuit is arranged so that a negative pulse applied to the controlelectrode of that electron tube of the bi-stable circuit which isconducting, will tend to decrease conduction therein, thereby resultingin an increase in potential at the anode, which in turn is coupled tothe control electrode of the other of the cross-coupled electron tubes,so as to tend to increase conduction therein. This action is cumulativeuntil the initially conducting electron tube becomes substantially cutoil, while the initially nonconducting electron tube becomes conducting.V

In a binary counter having a plurality of bi-stable circuits, the signaltransfer circuit, including the electron tube 3, may be used to formwhat is sometimes termed a permuted binary counter. In a permuted binarycounter, the maximum number of stable conditions of a. plurality ofbi-stable circuits is decreased so that the counter may be adapted tocount in a desired number system. For example, as noted above, fourbi-stable circuits may be employed to count to 16, but Where the decimalsystem of notation is adhered to, and the decimal digits are coded inbinary form, it is frequently desirable to count from 0 to 9 only. Byincluding the signal transfer circuit of our invention in such a binarycounter, any selected one of the bi-stable circuits may be inhibitedfrom responding to counting pulses by applying a signal from another ofthe bi-stable circuits to the control electrode of the signal transferelectron tube 3. By this means, the condition of conduction of one ofthe bi-stable circuits determines Whether the selected bi-stable circuitwill respond to incoming pulses.

Although the signal transfer circuit of our invention is shown inconnection with a bi-stable circuit which may be used as a portion of apermuted binary counter, the signal transfer circuit is not limitedthereto, since it may be employed to pass selectively, electrical pulsesto an output circuit Wherever such is required. In addition, theelectron tube types, the resistance values, and the power supplyvoltages given in Fig. 1 are exemplary only, being indicative of oneembodiment of the invention which has operated satisfactorily. In Fig. 1the values of the re- 3 sistancesare in ohms where K=1000 and thepotential values are in volts.

We claim: 1. A signal transfer circuit for. selectively passingnegative. pulses. to an output circuitiincluding in combination,.

an. electron tube. inchlding atleast a. cathode, a primary anode, acontrol electrode and one auxiliary anode located adjacent thev cathode,a cathode resistor connected between the cathode and a referencepotential, means energizing, the primary anode of. the electron tube toprovide. a current flow between the cathode and the primary anode, anoutput circuit. coupled to the. auxiliary anode, av source of negativepulses coupled across the cathode resistor, and. means coupled to thecontrol electrode for biasing. the electron, tube: to providev a voltageacross the cathode resistor of a polarity tending'to diminish conductionbetween the cathode and the auxiliary anode, whereby negative pulsesfrom; the source of. negative pulses are inhibited from passing totheoutput circuit.

2. A signal transfer circuit including in combination, an electron tubehaving atleast a. cathode, anode and control electrode, a diode sharingthe cathode of the electron tube, an output circuit coupled seriallywith the diode, acathode impedance coupled between; the cathode and areference potential, means: energizing the electron. tube to induce acurrent flow between. the cathode; and the anode, asource of negativepulses coupled across the cathode impedance, means biasing; the controlelectrode. of the electron tube to allow the. negative pulses to passthrough the diode to the output circuit during one. condition ofoperation, and means,- biasing; the'control electrode of the electron,tube to inhibit, the. passage of negative pulses through the diode tothe output circuit in another condition of operation. 7

3. In apparatus including a, binary counter having two stable conditionsof operatiomthe combination of a pair of cross-coupled. electron tubesconnected so that one of: the. electron tubes is conducting while theother electron tube is substantially cut off, a signal: transfer circuitineluding. an electron tube having at. least a cathode, a

at primary anode, a control electrode and a pair of auxiliary anodespositioned adjacent the cathode, means coupling the auxiliary anodes tothe cross-coupled electron tubes, a cathode resistor connected betweenthe cathode and a reference potential, means energizing the primaryanode positively with respect to the cathode, a source of negativepulses connected across the cathode resistor, means biasing the controlelectrode of the electron tube to permit negative pulses from thenegative pulse source to be applied tothe cross-coupled electron tubesvia the cathode and auxiliary anodes during one condition of operation,and said latter means biasing the control electrode of the electron tubeto provide a voltage across the cathode resistor which tends to diminishcurrent flow between the cathode and auxiliary anodes whereby negativepulses from the negative pulse source are inhibited from passing to thecross-coupled electron tubes via the cathode and auxiliary anodes inanother condition of operationv 4, A signal transfer circuit includingin combination, an electron tube having at least a cathode, anode,control electrode and auxiliary anode located adjacent the cathode,circuit means for supplying an operating potential to said anode, acathode resistance connecting said cathode to a commonreferencepotential, a source of negative pulses. coupled across said cathoderesistance, and a source of inhibiting signals coupled to said controlelectrode, said tube being responsive to said inhibiting signals tocontrol the conduction between the cathode and auxiliary anode inresponse to said negative pulses.

References Cited in the file of this patent UNITED STATES PATENTS2,466,959 Moore Apr. 12, 1949 2,478,683 Bliss Aug. 9, 1949 2,483,823George Oct. 4, 1949 2,535,377 Titterton Dec. 26, 1950 2,566,933Dickinson Sept. 4, 1951 2,622,193 Clayden Dec. 16, 1952 2,698,382 UglowDec. 28, 1954

